This invention relates to a data memory device and more particularly to a small portable memory device capable of storing data including secret codes or any other specified type of data.
To date, a data card has been proposed as a portable data recorder. Known data cards include a magnetic card provided with a magnetic recording medium and a bar code card impressed with optical patterns. With such data cards, a recording band is formed magnetically or by means of bar code patterns along the longer side of a rectangular data card. Recorded data is read out by scanning a recording band by a magnetic or optical reading head. Data is read out of a data card by a card reader which contacts a reading head with a recording band and causes both recording band and reading head to move relatively to each other.
An amount of data to be recorded in a data card is defined by a length of a recording band, or an area of a recording region, in case the recording band is formed of a plurality of tracks. To record a large amount of data, therefore, a recording band is extended to enlarge one side of a data card. With a card reader device, the reading head has to accurately scan an extended recording band. A card reader device for reading data from the data card has to be provided with a more complicated arrangement to cope with an increased amount of recorded data. The above-mentioned data card in which data is recorded magnetically or by means of optical patterns has the drawback that the recorded data is very likely to be damaged by external magnetic effects or soils.